The present invention relates generally to refrigeration compressors. More particularly, the present invention relates to a reciprocating piston type refrigeration compressor which incorporates capacity modulation by utilization of blocked suction.
Refrigeration and air conditioning systems are commonly operated under a wide range of loading conditions due to changing environmental conditions. In order to effectively and efficiently accomplish the desired cooling under these changing conditions, it is advantageous to incorporate a system which varies the capacity of the refrigeration compressor in the system.
A wide variety of systems have been developed in order to accomplish capacity modulation. The various types of unloading and capacity control found in the prior art for refrigeration compressors all have been subject to various drawbacks and/or durability issues. Some of these prior art systems have operated satisfactorily but they have required a substantial amount of external tubing or other components which are subject to damage during shipping and/or possible accidental damage after installation. In addition, the field labor required in the installation and maintenance of these external systems is subject to error which creates problems during actual operation and increases the field labor costs.
Other designs for capacity modulation systems are installed during the manufacture of the compressor. These designs have all of the major components internal to the compressor itself except for a single component which is typically the only element to require servicing during the expectable life of the compressor. This single external component is constructed such that it is easily accessible for service while still being positioned to limit the danger of accidental damage.
While the prior art internal systems have proven to operate satisfactorily, there is still a need to improve both the reliability and durability of these capacity modulation systems.
The present invention provides the art with a capacity modulation system which utilizes a piston for blocking the suction inlet to reduce the capacity of the compressor. The high-pressure gas which is supplied to the piston during activation is throttled in order to reduce the piston impact velocity. The reduction in the piston impact velocity improves the reliability and durability of the piston, the piston seals and the piston seat.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.